What are VServers

The [http://linux-vserver.org Linux VServer Project] provides multiple Linux environments running inside a single Linux kernel.

You can think of it as a bit like running a new system inside a chroot, but with a different host name and IP address, a de-fanged root user, and configurable resource management. This is a similar feature to jails on FreeBSD and containers on Solaris 10+.

VServers are a different approach to the popular [http://www.xen-source.com XEN] Hypervisor; with XEN you end up with a kernel for each virtual server; VServers do not. So, with VServer you have less (virtually no) overhead, on the other hand you also have fewer features - it is currently impossible to have a VServer with a different time set to the host system, for instance. However it is possible to run a different time zone, as that is a purely user-space feature. The design of UNIX in general mean that for the vast majority of applications, this virtualisation technique is perfectly adequate.

Note that Xen and VServer are orthogonal approaches - that is, it is perfectly possible and sometimes even sensible to run Xen virtual machines on a Linux system, then Linux VServers within those Xen machines.

Installation

Installation is quite simple - you need:

• Kernel with VServer patch
• util-vserver
• vserver-debiantools

You can install these packages if you add the following lines to your sources.list:

• dapper

  deb      http://ubuntu.uni-klu.ac.at/ubuntu.uniklu/  dapper uniklu-vserver
  #deb-src http://ubuntu.uni-klu.ac.at/ubuntu.uniklu/  dapper uniklu-vserver

The uniklu archives are signed - if you want get rid of apt-get warnings: {{{$ wget http://ubuntu.uni-klu.ac.at/uniklu-debuild.pub $ sudo apt-key add uniklu-debuild.pub }}}

To install the VServer Kernel and utils enter:

• dapper

  # apt-get install linux-image-2.6.15-(dapper_abi+1)-686
  # apt-get install util-vserver vserver-debiantools

You should get the following revisions

• dapper

  kernel	-(dapper_abi+1)-2.6.15-(dapper_abi+1).(dapper_release)vs
  util-vserver	>= 0.30.210-0uk
  vserver-debiantools	>= 0.2.6

The vserver-debiantools do not work 100% but should help you setting your first vserver quickly - see [http://support.uni-klu.ac.at/VServer Uniklu VServer Info]

The Kernel is the standard Ubuntu Kernel with the Vserver patch applied.

• dapper: Vserver patch >= 2.0.2-rc13 for kernel-2.6.15

The Kernel and binaries are available for i386 and amd64

It is possible and supported to run 32bit i386 VServers on an amd64 VServer Kernel.

Distributed Remote Block Device (DRBD)

[http://www.drbd.org DRBD] can be used with VServer to build simple, robust and cheap HA solutions with disaster failover capabilty to a remote location.

Simply put your VServers on a DRBD and let heartbeat in another building takeover the DRBD and start your VServers.

DRBD utils and kernel modules for the VServer enabled kernels are available in the above archive:

apt-get install drbd0.7-module-2.6.15-(dapper_abi+1)-arch drbd0.7-utils 

Build Yourself

I've created a tgz of the diffs and build script i'm using for building the kernel debs.

{{{$ wget http://ubuntu.uni-klu.ac.at/ubuntu.uniklu/dists/dapper/uniklu-vserver/vserver-image-build.tgz $ tar -xzf vserver-image-build.tgz $ cd linux-vserver-2.6.15 $ ./kbuild.sh }}}

Links

• [http://linux-vserver.org Linux VServer Project]

• [http://support.uni-klu.ac.at/VServer Uniklu VServer info]

• [http://www.howtoforge.com/linux_vserver_debian Linux VServer on Debian Sarge]

• [http://www.drbd.org DRBD Homepage]

• [http://linux-vserver.org/Vserver+DRBD VServer and DRBD info]

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